Patent GB-819428-A (GB)
Title: Water separators
IPC: F24F3/14
Filed: 1956-01-27
Abstract: 819,428. Ventilating aircraft. UNITED AIRCRAFT CORPORATON. Jan. 27, 1956 [Feb. 17, 1955], No. 2725/56. Class 137 [Also in Group XXIX] In a de-icing control for a device for separating moisture from a supply of air, the introduction of heated air to the entrance of the separator is controlled by means responsive to a change in the pressure drop across a portion of the separator due to icing of the separator. As shown, in an arrangement for supplying conditioned air to an aircraft cabin 20, hot air from a compressor 10 is fed through pipes 12, 14, a regulating valve 134 and a pipe 36 to a cabin supply pipe 18 to mix with a supply of cooled air derived from the compressor 10 and cooled in parallel pipe lines 16, 24, 50, 51, including a heat exchanger 22, a cooling turbine 26 and a water separator 52 with a coalescer 66 and a collector 70. The coalescer 66, upon becoming iced up, is thawed out by introducing hot air in a pipe 96 from the compressor 10 into the turbine discharge pipe 50 upstream of the coalescer. The introduction of the hot air into the pipe 50 is controlled by mechanism which is sensitive to the changes in pressure across the coalescer due to icing and which is in the form of a fluid pressure controlling device analogous to an electrial Wheatstone bridge having one arm incorporating the coalescer 66 and the collector 70 and the other arm with variable and fixed restrictions 80, 78 respectively. The detector, connected between the mid-points 82, 84 of the bridge is in the form of a pressure responsive diaphragm 86 centred by springs 88, 90 enclosed in a pressure cham- 'ber. The diaphragm 86 controls a valve 92 which regulates the escape of air through an outlet nozzle 94 in the hot air line 96 and thus the pressure in a chamber 100 which is connected between the nozzle 94 and a restriction 98 in the line 96. A spring-loaded diaphragm 102 in the chamber 100 is connected to a valve which regulates the size of the variable restriction 80 and also to a valve 104 which controls the re-introduction of hot air from the line 96 to the turbine discharge pipe 50. The valve in the restriction 80 is preset so that the pressure developed across it is equal to that developed across the coalescer 66 when fully thawed out, thus with the fixed restriction 78 chosen to drop a pressure equal to that dropped across the collector 70 the bridge is balanced. In this condition the pressure in the hot air line 96 is released through the nozzle 94. As the coalescer commences to ice up the pressure drop across it increases, the pressure P2 at the point 82 becoming correspondingly less than the pressure P4 at the point 84 and the valve 92 thereupon being moved upwardly to close the nozzle 94 which increases the pressure in the chamber 100. The diaphragm 102 is now urged in a direction which tends to close the valve in the restriction 80 in an unsuccessful attempt to balance the pressures P2 and P4, and also to open the valve 104 to admit hot air into the pipe 50 in an amount which is proportional to the amount of icing up in the coalescer. The valve 104 remains open to supply hot air to the pipe 50 as long as the coalescer is blocked by ice, but as soon as it is thawed out the bridge reverts to its balanced state and the valve 104 cuts off the supply of hot air to the pipe 50. The valve 134 in the hot air supply pipe 14 is controlled by mechanism which is responsive to a temperature sensitive element 40 in the cabin 20. The cooling for the heat exchanger 22 is introduced through a pipe 28 which may be supplied with ram air. After passing through the heat exchanger the cooling air passes through a pipe 30, a fan 32, driven by the turbines 26 and is discharged overboard through a pipe 34. The water separator may have a by-pass pipe 74 including a valve 76 which may be actuated by the ambient pressure in the cabin 10, the latter being provided with a relief valve 38.